Mary and Dan started running at the same time. After 20 minutes behind them with the speed of 18km/h Alex started running.
Calculate, after how many minutes Alex reached Mary, if we know that he reached Dan after 30 min, and the speed ratio between Mary and Dan was 7 : 6 !
Calculate, after how many minutes Alex reached Mary, if we know that he reached Dan after 30 min, and the speed ratio between Mary and Dan was 7 : 6 !
